Based on the longer Wikipedia page .
The Smithy code is series of letters embedded, as a private amusement, within the April 2006 approved judgement of Mr Justice Peter Smith on the The Da Vinci Code copyright case. It was first broken by Dan Tench, a lawyer who writes on media issues for The Guardian, after he received a series of email clues about it from Justice Smith.
The letters in question are part of the actual text of the judgement, but italicised in contrast to the rest of the text and should read "Jackie Fisher who are you? Dreadnought" - but read JACKIEFISTERWHOAREYOUDREADNOUGH.
The cipher was a type of polyalphabetic cipher known as a Variant Beaufort, using a keyword based on the Fibonacci sequence, namely AAYCEHMU. This is the reverse of the Vigenère cipher, which here enables decryption rather than encryption.